The invention pertains to methods of forming and using platinum-containing materials, and to circuitry incorporating roughened layers of platinum.
Platinum is a candidate for utilization as a conductive material in advanced semiconductor processing. Platinum can be utilized in an elemental form, or as an alloy (such as, for example, rhodium/platinum), and can be deposited onto a substrate by, for example, sputter deposition or chemical vapor deposition (CVD) methods. Platinum is typically formed to have a relatively smooth upper surface. Such smooth upper surface can be advantageous in, for example, applications in which circuitry is formed over the platinum layer. Specifically, the relatively smooth surface can provide a substantially planar platform upon which other circuitry is formed. However, there can be advantages to incorporating roughened conductive layers into integrated circuitry in applications where high surface area is desired, as with capacitor electrodes. Accordingly, it would be desirable to develop methods of forming platinum layers having roughened outer surfaces.
In another aspect of the prior art, platinum-comprising materials are frequently utilized as catalysts in, for example, the petroleum industry, as well as in, for example, automobile exhaust systems. Frequently, an efficiency of a catalyst can be improved by enhancing a surface area of the catalyst. Accordingly, it would be desirable to develop methods of enhancing surface area of platinum-comprising materials.
In one aspect, the invention encompasses a method of forming a roughened layer of platinum. A substrate is provided within a reaction chamber. An oxidizing gas is flowed into the reaction chamber, and a platinum precursor is flowed into the chamber. Platinum is deposited from the platinum precursor over the substrate in the presence of the oxidizing gas. A temperature within the chamber is maintained at from about 0xc2x0 C. to less than 300xc2x0 C. during the depositing.
In another aspect, the invention encompasses a circuit comprising a roughened platinum layer over a substrate. The roughened platinum layer has a continuous surface characterized by columnar pedestals.
In yet another aspect, the invention encompasses a platinum catalyst characterized by a continuous outer surface portion of the platinum having a plurality of columnar pedestals that are at least about 400 xc3x85 tall. The surface portion covers an area that is at least about 4xc3x97106 square Angstroms.